What is a Load Balancer?
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15-Jan-2026
Updated on 15-Jan-2026
ICSM
15-Jan-2026A Load Balancer is a system (hardware or software) that distributes incoming network traffic across multiple servers to ensure high availability, scalability, performance, and reliability of an application
Instead of all users hitting one server, the load balancer decides which server should handle each request.
Why Load Balancers Are Needed
Without a load balancer:
With a load balancer:
Basic Architecture (Image / Diagram)
Working Process of a Load Balancer (Step by Step)
1. Client Sends Request
A user opens a website or API:
The request first goes to the Load Balancer, not directly to a server.
2. Health Check
The load balancer continuously checks:
Unhealthy servers are removed from rotation.
3. Load Balancing Algorithm Selection
The load balancer chooses a server using an algorithm such as:
4. Request Forwarding
The request is forwarded to the selected server.
5. Server Responds
The chosen server processes the request and sends the response back through the load balancer to the client.
Request Flow Diagram (Working Process)
Common Load Balancing Algorithms
1. Round Robin
Requests are distributed sequentially.
Best for: servers with equal capacity.
2. Least Connections
Request goes to the server with fewest active connections.
Best for: long-running requests.
3. IP Hash
Same client IP always goes to the same server.
Best for: session-based applications.
Types of Load Balancers
1. Hardware Load Balancer
2. Software Load Balancer
3. Cloud Load Balancer
Layer-wise Load Balancing
Layer 4 (Transport Layer)
Example:
Real-World Example
E-commerce Website Sale Day
Without Load Balancer:
With Load Balancer:
Key Benefits Summary